From reflection to absorption: Improving light harvesting of dye sensitized solar cells with Cu nanowires as reflectors

Abstract

Back reflectors have emerged as an effective approach to improve the light harvesting ability of photoanodes, which is considered as an obstacle to high performing photovoltaic (PV) devices. Considering the light scattering phenomenon of one dimensional (1D) material playing significant role in back-reflection, the present work demonstrated the use of 1D copper nanowires (Cu NWs) as light reflectors in dye sensitized solar cells (DSSCs) towards improving their PV performance. Cu NWs were synthesized using solvothermal method and characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDX) mapping. The criteria behind using Cu NWs reflectors is to utilize the unabsorbed incident light, which is usually transmitted through the platinum (Pt) counter electrode (CE) in a typical DSSC, to enhance the light harvesting ability of photoanodes and hence their PV performance. We have observed a 10.2% enhancement in the power conversion efficiency (PCE) of Cu reflector based DSSCs (6.69%) relative to reference DSSCs (6.07%). The improved PV performance of Cu reflector based DSSCs is supported by the reduced charge transfer resistances at different interfacial layers obtained from the electrochemical impedance spectroscopy (EIS) measurements. By demonstrating the remarkable cost-effectiveness of Cu NWs, our findings pave the way for the widespread implementation of reflectors in next-generation photovoltaic devices, enabling enhanced performance across diverse environmental settings.